Coronary sinus occlusion enhances coronary collateral flow and reduces subendocardial ischemia

On the hypothesis that coronary sinus occlusion (CSO) may reduce myocardial ischemia, we examined the effects of CSO on coronary collateral blood flow and on the distribution of regional myocardial blood flow (RMBF) in dogs. Thirty-eight anesthetized dogs underwent occlusion of the left anterior descending coronary artery with or without CSO and intact vasomotor tone. We measured RMBF and intramyocardial pressure (IMP) in the subendocardium (Endo) and subepicardium (Epi) separately. With intact vasomotor tone, CSO during ischemia significantly increased RMBF in the ischemic region (IR), particularly in Endo from 0.17 +/- 0.03 to 0.33 +/- 0.05 ml . min(-1) . g(-1) (P< 0.05), and increased the Endo/Epi from 0.59 +/- 0.10 to 1.15 +/- 0.15 (P< 0.01). These effects of CSO were partially abolished by adenosine. However, the Endo/Epi was still increased from 0.90 +/- 0.13 to 2.09 +/- 0.30 (P< 0.01). The changes in RMBF in IR were significantly correlated with the peak CS pressure during CSO. The Endo/Epi of IMP in IR was significantly decreased during CSO. In conclusion, CSO potentially enhances coronary collateral flow, and preserves the ischemic myocardium, especially in Endo.